A plurality of power semiconductor chips is mounted on a metal substrate interposing an insulating layer therebetween in a power semiconductor module. The power semiconductor chip includes IGBT (Insulated Gate Bipolar Transistor), MOSFET (Metal Oxide Field Effect Transistor), or a diode, for example.
It is desirable that an inductance of an inside of the power semiconductor module be reduced as an over-voltage may be generated during high speed switching when the inductance of the inside is large, and thereby, cause a breakdown of the power semiconductor module. The switching loss becomes large even when the power semiconductor chip is not switched at a high speed.